This invention relates to a gradient index (GRIN) lens, instruments using such lenses, and method for making such lens.
In recent years, optical fiber technology for telecommunication has progressed rapidly to replace other means for telecommunication such as copper wires and microwave. In many telecommunication applications, it is important for the devices used to be small enough to fit into a limited space. GRIN lenses are widely used in fiber optic components such as switches, isolators, wavelength division multiplexers (WDM's), and circulators. However, as explained below, it is desirable for the index of refraction of a GRIN lens to vary gradually from the axis of the lens radially towards its periphery. In order to make such lens, a glass rod of sufficient diameter is usually employed, so that the resulting lens having adequate optical performance is larger than a certain size. The size of the lenses is often one of the limiting factors of component size. It is therefore desirable to reduce the size of GRIN lenses and still preserve its optical performance.